Arrhythmia is an abnormal rhythm of the heart. A tachyarrhythmia is an abnormally fast heart rhythm. A tachyarrhythmia originating in the ventricular region of the heart is called a ventricular tachyarrhythmia (VT). Ventricular tachyarrhythmia can produce symptoms of fainting, dizziness, weakness, blind spots, and potentially, unconsciousness and cardiac arrest. A tachyarrhythmia that does not originate from the ventricular region of the heart is called a supraventricular tachyarrhythmia (SVT). An SVT episode typically originates from an impulse arising in the atrium, the atrioventricular node (AV node), or the bundle of His. SVT episodes tend to be much less lethal than VT episodes.
Treatment for cardiac tachyarrhythmia can be administered by a medical device, such as a pacemaker or a defibrillator, which can be implanted in the human body. These devices can be configured to sense an intrinsic electrical heart signal and analyze the signal to determine whether a tachyarrhythmia is occurring. Such devices can also be configured to deliver antitachyarrhythmia therapy, such as electric stimulation. Improved cardiac rhythm management methods and systems are needed.